Sheila conducts an investigation to see how the amount of salt dissolved in water affects the density of the water. Which statement best describes the correct plan for her procedure? A The density and the amount of water are controls, and the amount of salt and the type of salt are variables.

B The amount of water and the amount of salt are controls, and the type of salt and the density are variables.

C The type of salt and the amount of water are controls, and the amount of salt and the density are variables.

D The type of salt and the density of water are controls, and the amount of salt and the amount of water are variables.